The invention relates to vacuum filter discs used to support filter bags in slurry separation of iron ore from water. In filter systems of this type, a plurality of filter discs in the general shape of circular ring sectors are arranged around a rotational axis to form a circular disc. Each sector is provided with its own filter media in the form of a fabric bag which encloses the sector. In use, the disc is rotated through the slurry and the discs communicate with a vacuum manifold. The vacuum withdraws water through the filter and a paste or cake builds up on the surface of the filter bag and is subsequently blown off onto a discharge conveyor.
Some prior art filter sectors have been constructed of spaced steel plates secured together, with the plates being perforated to enable communication of the vacuum manifold with the interior of the filter bag. The perforated iron or steel sectors were subject to corrosion. Other prior art filter sectors are formed from plastic with closed bottom radial grooves which delivered the liquid to the manifold. The plastic sectors do not effectively withstand the mechanical forces to which the sector is subjected to during use and their life is limited. The hard surfaces of the plastic and steel sectors did not provide sufficiently large open area beneath the bag surface for efficient fluid separation and the hard surfaces of these sectors resulted in quick wear of the filter bags.